libavcodec provides some generic global options, which can be set on
all the encoders and decoders. In addition each codec may support
so-called private options, which are specific for a given codec.

Sometimes, a global option may only affect a specific kind of codec,
and may be nonsensical or ignored by another, so you need to be aware
of the meaning of the specified options. Also some options are
meant only for decoding or encoding.

Options may be set by specifying -optionvalue in the
FFmpeg tools, or by setting the value explicitly in the
AVCodecContext options or using the libavutil/opt.h API
for programmatic use.

The list of supported options follow:

b integer (encoding,audio,video)

Set bitrate in bits/s. Default value is 200K.

ab integer (encoding,audio)

Set audio bitrate (in bits/s). Default value is 128K.

bt integer (encoding,video)

Set video bitrate tolerance (in bits/s). In 1-pass mode, bitrate
tolerance specifies how far ratecontrol is willing to deviate from the
target average bitrate value. This is not related to min/max
bitrate. Lowering tolerance too much has an adverse effect on quality.

flags flags (decoding/encoding,audio,video,subtitles)

Set generic flags.

Possible values:

‘mv4’

Use four motion vector by macroblock (mpeg4).

‘qpel’

Use 1/4 pel motion compensation.

‘loop’

Use loop filter.

‘qscale’

Use fixed qscale.

‘pass1’

Use internal 2pass ratecontrol in first pass mode.

‘pass2’

Use internal 2pass ratecontrol in second pass mode.

‘gray’

Only decode/encode grayscale.

‘emu_edge’

Do not draw edges.

‘psnr’

Set error[?] variables during encoding.

‘truncated’

‘ildct’

Use interlaced DCT.

‘low_delay’

Force low delay.

‘global_header’

Place global headers in extradata instead of every keyframe.

‘bitexact’

Only write platform-, build- and time-independent data. (except (I)DCT).
This ensures that file and data checksums are reproducible and match between
platforms. Its primary use is for regression testing.

‘aic’

Apply H263 advanced intra coding / mpeg4 ac prediction.

‘cbp’

Deprecated, use mpegvideo private options instead.

‘qprd’

Deprecated, use mpegvideo private options instead.

‘ilme’

Apply interlaced motion estimation.

‘cgop’

Use closed gop.

me_method integer (encoding,video)

Set motion estimation method.

Possible values:

‘zero’

zero motion estimation (fastest)

‘full’

full motion estimation (slowest)

‘epzs’

EPZS motion estimation (default)

‘esa’

esa motion estimation (alias for full)

‘tesa’

tesa motion estimation

‘dia’

dia motion estimation (alias for epzs)

‘log’

log motion estimation

‘phods’

phods motion estimation

‘x1’

X1 motion estimation

‘hex’

hex motion estimation

‘umh’

umh motion estimation

‘iter’

iter motion estimation

extradata_size integer

Set extradata size.

time_base rational number

Set codec time base.

It is the fundamental unit of time (in seconds) in terms of which
frame timestamps are represented. For fixed-fps content, timebase
should be 1 / frame_rate and timestamp increments should be
identically 1.

g integer (encoding,video)

Set the group of picture (GOP) size. Default value is 12.

ar integer (decoding/encoding,audio)

Set audio sampling rate (in Hz).

ac integer (decoding/encoding,audio)

Set number of audio channels.

cutoff integer (encoding,audio)

Set cutoff bandwidth. (Supported only by selected encoders, see
their respective documentation sections.)

frame_size integer (encoding,audio)

Set audio frame size.

Each submitted frame except the last must contain exactly frame_size
samples per channel. May be 0 when the codec has
CODEC_CAP_VARIABLE_FRAME_SIZE set, in that case the frame size is not
restricted. It is set by some decoders to indicate constant frame
size.

frame_number integer

Set the frame number.

delay integer

qcomp float (encoding,video)

Set video quantizer scale compression (VBR). It is used as a constant
in the ratecontrol equation. Recommended range for default rc_eq:
0.0-1.0.

qblur float (encoding,video)

Set video quantizer scale blur (VBR).

qmin integer (encoding,video)

Set min video quantizer scale (VBR). Must be included between -1 and
69, default value is 2.

qmax integer (encoding,video)

Set max video quantizer scale (VBR). Must be included between -1 and
1024, default value is 31.

qdiff integer (encoding,video)

Set max difference between the quantizer scale (VBR).

bf integer (encoding,video)

Set max number of B frames between non-B-frames.

Must be an integer between -1 and 16. 0 means that B-frames are
disabled. If a value of -1 is used, it will choose an automatic value
depending on the encoder.

Default value is 0.

b_qfactor float (encoding,video)

Set qp factor between P and B frames.

rc_strategy integer (encoding,video)

Set ratecontrol method.

b_strategy integer (encoding,video)

Set strategy to choose between I/P/B-frames.

ps integer (encoding,video)

Set RTP payload size in bytes.

mv_bits integer

header_bits integer

i_tex_bits integer

p_tex_bits integer

i_count integer

p_count integer

skip_count integer

misc_bits integer

frame_bits integer

codec_tag integer

bug flags (decoding,video)

Workaround not auto detected encoder bugs.

Possible values:

‘autodetect’

‘old_msmpeg4’

some old lavc generated msmpeg4v3 files (no autodetection)

‘xvid_ilace’

Xvid interlacing bug (autodetected if fourcc==XVIX)

‘ump4’

(autodetected if fourcc==UMP4)

‘no_padding’

padding bug (autodetected)

‘amv’

‘ac_vlc’

illegal vlc bug (autodetected per fourcc)

‘qpel_chroma’

‘std_qpel’

old standard qpel (autodetected per fourcc/version)

‘qpel_chroma2’

‘direct_blocksize’

direct-qpel-blocksize bug (autodetected per fourcc/version)

‘edge’

edge padding bug (autodetected per fourcc/version)

‘hpel_chroma’

‘dc_clip’

‘ms’

Workaround various bugs in microsoft broken decoders.

‘trunc’

trancated frames

lelim integer (encoding,video)

Set single coefficient elimination threshold for luminance (negative
values also consider DC coefficient).

celim integer (encoding,video)

Set single coefficient elimination threshold for chrominance (negative
values also consider dc coefficient)

strict integer (decoding/encoding,audio,video)

Specify how strictly to follow the standards.

Possible values:

‘very’

strictly conform to an older more strict version of the spec or reference software

‘strict’

strictly conform to all the things in the spec no matter what consequences

‘normal’

‘unofficial’

allow unofficial extensions

‘experimental’

allow non standardized experimental things, experimental
(unfinished/work in progress/not well tested) decoders and encoders.
Note: experimental decoders can pose a security risk, do not use this for
decoding untrusted input.

b_qoffset float (encoding,video)

Set QP offset between P and B frames.

err_detect flags (decoding,audio,video)

Set error detection flags.

Possible values:

‘crccheck’

verify embedded CRCs

‘bitstream’

detect bitstream specification deviations

‘buffer’

detect improper bitstream length

‘explode’

abort decoding on minor error detection

‘ignore_err’

ignore decoding errors, and continue decoding.
This is useful if you want to analyze the content of a video and thus want
everything to be decoded no matter what. This option will not result in a video
that is pleasing to watch in case of errors.

‘careful’

consider things that violate the spec and have not been seen in the wild as errors

‘compliant’

consider all spec non compliancies as errors

‘aggressive’

consider things that a sane encoder should not do as an error

has_b_frames integer

block_align integer

mpeg_quant integer (encoding,video)

Use MPEG quantizers instead of H.263.

qsquish float (encoding,video)

How to keep quantizer between qmin and qmax (0 = clip, 1 = use
differentiable function).

Set min bitrate tolerance (in bits/s). Most useful in setting up a CBR
encode. It is of little use elsewise.

bufsize integer (encoding,audio,video)

Set ratecontrol buffer size (in bits).

rc_buf_aggressivity float (encoding,video)

Currently useless.

i_qfactor float (encoding,video)

Set QP factor between P and I frames.

i_qoffset float (encoding,video)

Set QP offset between P and I frames.

rc_init_cplx float (encoding,video)

Set initial complexity for 1-pass encoding.

dct integer (encoding,video)

Set DCT algorithm.

Possible values:

‘auto’

autoselect a good one (default)

‘fastint’

fast integer

‘int’

accurate integer

‘mmx’

‘altivec’

‘faan’

floating point AAN DCT

lumi_mask float (encoding,video)

Compress bright areas stronger than medium ones.

tcplx_mask float (encoding,video)

Set temporal complexity masking.

scplx_mask float (encoding,video)

Set spatial complexity masking.

p_mask float (encoding,video)

Set inter masking.

dark_mask float (encoding,video)

Compress dark areas stronger than medium ones.

idct integer (decoding/encoding,video)

Select IDCT implementation.

Possible values:

‘auto’

‘int’

‘simple’

‘simplemmx’

‘simpleauto’

Automatically pick a IDCT compatible with the simple one

‘arm’

‘altivec’

‘sh4’

‘simplearm’

‘simplearmv5te’

‘simplearmv6’

‘simpleneon’

‘simplealpha’

‘ipp’

‘xvidmmx’

‘faani’

floating point AAN IDCT

slice_count integer

ec flags (decoding,video)

Set error concealment strategy.

Possible values:

‘guess_mvs’

iterative motion vector (MV) search (slow)

‘deblock’

use strong deblock filter for damaged MBs

‘favor_inter’

favor predicting from the previous frame instead of the current

bits_per_coded_sample integer

pred integer (encoding,video)

Set prediction method.

Possible values:

‘left’

‘plane’

‘median’

aspect rational number (encoding,video)

Set sample aspect ratio.

sar rational number (encoding,video)

Set sample aspect ratio. Alias to aspect.

debug flags (decoding/encoding,audio,video,subtitles)

Print specific debug info.

Possible values:

‘pict’

picture info

‘rc’

rate control

‘bitstream’

‘mb_type’

macroblock (MB) type

‘qp’

per-block quantization parameter (QP)

‘mv’

motion vector

‘dct_coeff’

‘green_metadata’

display complexity metadata for the upcoming frame, GoP or for a given duration.

‘skip’

‘startcode’

‘pts’

‘er’

error recognition

‘mmco’

memory management control operations (H.264)

‘bugs’

‘vis_qp’

visualize quantization parameter (QP), lower QP are tinted greener

‘vis_mb_type’

visualize block types

‘buffers’

picture buffer allocations

‘thread_ops’

threading operations

‘nomc’

skip motion compensation

cmp integer (encoding,video)

Set full pel me compare function.

Possible values:

‘sad’

sum of absolute differences, fast (default)

‘sse’

sum of squared errors

‘satd’

sum of absolute Hadamard transformed differences

‘dct’

sum of absolute DCT transformed differences

‘psnr’

sum of squared quantization errors (avoid, low quality)

‘bit’

number of bits needed for the block

‘rd’

rate distortion optimal, slow

‘zero’

0

‘vsad’

sum of absolute vertical differences

‘vsse’

sum of squared vertical differences

‘nsse’

noise preserving sum of squared differences

‘w53’

5/3 wavelet, only used in snow

‘w97’

9/7 wavelet, only used in snow

‘dctmax’

‘chroma’

subcmp integer (encoding,video)

Set sub pel me compare function.

Possible values:

‘sad’

sum of absolute differences, fast (default)

‘sse’

sum of squared errors

‘satd’

sum of absolute Hadamard transformed differences

‘dct’

sum of absolute DCT transformed differences

‘psnr’

sum of squared quantization errors (avoid, low quality)

‘bit’

number of bits needed for the block

‘rd’

rate distortion optimal, slow

‘zero’

0

‘vsad’

sum of absolute vertical differences

‘vsse’

sum of squared vertical differences

‘nsse’

noise preserving sum of squared differences

‘w53’

5/3 wavelet, only used in snow

‘w97’

9/7 wavelet, only used in snow

‘dctmax’

‘chroma’

mbcmp integer (encoding,video)

Set macroblock compare function.

Possible values:

‘sad’

sum of absolute differences, fast (default)

‘sse’

sum of squared errors

‘satd’

sum of absolute Hadamard transformed differences

‘dct’

sum of absolute DCT transformed differences

‘psnr’

sum of squared quantization errors (avoid, low quality)

‘bit’

number of bits needed for the block

‘rd’

rate distortion optimal, slow

‘zero’

0

‘vsad’

sum of absolute vertical differences

‘vsse’

sum of squared vertical differences

‘nsse’

noise preserving sum of squared differences

‘w53’

5/3 wavelet, only used in snow

‘w97’

9/7 wavelet, only used in snow

‘dctmax’

‘chroma’

ildctcmp integer (encoding,video)

Set interlaced dct compare function.

Possible values:

‘sad’

sum of absolute differences, fast (default)

‘sse’

sum of squared errors

‘satd’

sum of absolute Hadamard transformed differences

‘dct’

sum of absolute DCT transformed differences

‘psnr’

sum of squared quantization errors (avoid, low quality)

‘bit’

number of bits needed for the block

‘rd’

rate distortion optimal, slow

‘zero’

0

‘vsad’

sum of absolute vertical differences

‘vsse’

sum of squared vertical differences

‘nsse’

noise preserving sum of squared differences

‘w53’

5/3 wavelet, only used in snow

‘w97’

9/7 wavelet, only used in snow

‘dctmax’

‘chroma’

dia_size integer (encoding,video)

Set diamond type & size for motion estimation.

last_pred integer (encoding,video)

Set amount of motion predictors from the previous frame.

preme integer (encoding,video)

Set pre motion estimation.

precmp integer (encoding,video)

Set pre motion estimation compare function.

Possible values:

‘sad’

sum of absolute differences, fast (default)

‘sse’

sum of squared errors

‘satd’

sum of absolute Hadamard transformed differences

‘dct’

sum of absolute DCT transformed differences

‘psnr’

sum of squared quantization errors (avoid, low quality)

‘bit’

number of bits needed for the block

‘rd’

rate distortion optimal, slow

‘zero’

0

‘vsad’

sum of absolute vertical differences

‘vsse’

sum of squared vertical differences

‘nsse’

noise preserving sum of squared differences

‘w53’

5/3 wavelet, only used in snow

‘w97’

9/7 wavelet, only used in snow

‘dctmax’

‘chroma’

pre_dia_size integer (encoding,video)

Set diamond type & size for motion estimation pre-pass.

subq integer (encoding,video)

Set sub pel motion estimation quality.

dtg_active_format integer

me_range integer (encoding,video)

Set limit motion vectors range (1023 for DivX player).

ibias integer (encoding,video)

Set intra quant bias.

pbias integer (encoding,video)

Set inter quant bias.

color_table_id integer

global_quality integer (encoding,audio,video)

coder integer (encoding,video)

Possible values:

‘vlc’

variable length coder / huffman coder

‘ac’

arithmetic coder

‘raw’

raw (no encoding)

‘rle’

run-length coder

‘deflate’

deflate-based coder

context integer (encoding,video)

Set context model.

slice_flags integer

mbd integer (encoding,video)

Set macroblock decision algorithm (high quality mode).

Possible values:

‘simple’

use mbcmp (default)

‘bits’

use fewest bits

‘rd’

use best rate distortion

stream_codec_tag integer

sc_threshold integer (encoding,video)

Set scene change threshold.

lmin integer (encoding,video)

Set min lagrange factor (VBR).

lmax integer (encoding,video)

Set max lagrange factor (VBR).

nr integer (encoding,video)

Set noise reduction.

rc_init_occupancy integer (encoding,video)

Set number of bits which should be loaded into the rc buffer before
decoding starts.

flags2 flags (decoding/encoding,audio,video)

Possible values:

‘fast’

Allow non spec compliant speedup tricks.

‘sgop’

Deprecated, use mpegvideo private options instead.

‘noout’

Skip bitstream encoding.

‘ignorecrop’

Ignore cropping information from sps.

‘local_header’

Place global headers at every keyframe instead of in extradata.

‘chunks’

Frame data might be split into multiple chunks.

‘showall’

Show all frames before the first keyframe.

‘skiprd’

Deprecated, use mpegvideo private options instead.

‘export_mvs’

Export motion vectors into frame side-data (see AV_FRAME_DATA_MOTION_VECTORS)
for codecs that support it. See also doc/examples/export_mvs.c.

error integer (encoding,video)

qns integer (encoding,video)

Deprecated, use mpegvideo private options instead.

threads integer (decoding/encoding,video)

Set the number of threads to be used, in case the selected codec
implementation supports multi-threading.

Possible values:

‘auto, 0’

automatically select the number of threads to set

Default value is ‘auto’.

me_threshold integer (encoding,video)

Set motion estimation threshold.

mb_threshold integer (encoding,video)

Set macroblock threshold.

dc integer (encoding,video)

Set intra_dc_precision.

nssew integer (encoding,video)

Set nsse weight.

skip_top integer (decoding,video)

Set number of macroblock rows at the top which are skipped.

skip_bottom integer (decoding,video)

Set number of macroblock rows at the bottom which are skipped.

profile integer (encoding,audio,video)

Possible values:

‘unknown’

‘aac_main’

‘aac_low’

‘aac_ssr’

‘aac_ltp’

‘aac_he’

‘aac_he_v2’

‘aac_ld’

‘aac_eld’

‘mpeg2_aac_low’

‘mpeg2_aac_he’

‘mpeg4_sp’

‘mpeg4_core’

‘mpeg4_main’

‘mpeg4_asp’

‘dts’

‘dts_es’

‘dts_96_24’

‘dts_hd_hra’

‘dts_hd_ma’

level integer (encoding,audio,video)

Possible values:

‘unknown’

lowres integer (decoding,audio,video)

Decode at 1= 1/2, 2=1/4, 3=1/8 resolutions.

skip_threshold integer (encoding,video)

Set frame skip threshold.

skip_factor integer (encoding,video)

Set frame skip factor.

skip_exp integer (encoding,video)

Set frame skip exponent.
Negative values behave identical to the corresponding positive ones, except
that the score is normalized.
Positive values exist primarily for compatibility reasons and are not so useful.

skipcmp integer (encoding,video)

Set frame skip compare function.

Possible values:

‘sad’

sum of absolute differences, fast (default)

‘sse’

sum of squared errors

‘satd’

sum of absolute Hadamard transformed differences

‘dct’

sum of absolute DCT transformed differences

‘psnr’

sum of squared quantization errors (avoid, low quality)

‘bit’

number of bits needed for the block

‘rd’

rate distortion optimal, slow

‘zero’

0

‘vsad’

sum of absolute vertical differences

‘vsse’

sum of squared vertical differences

‘nsse’

noise preserving sum of squared differences

‘w53’

5/3 wavelet, only used in snow

‘w97’

9/7 wavelet, only used in snow

‘dctmax’

‘chroma’

border_mask float (encoding,video)

Increase the quantizer for macroblocks close to borders.

mblmin integer (encoding,video)

Set min macroblock lagrange factor (VBR).

mblmax integer (encoding,video)

Set max macroblock lagrange factor (VBR).

mepc integer (encoding,video)

Set motion estimation bitrate penalty compensation (1.0 = 256).

skip_loop_filter integer (decoding,video)

skip_idct integer (decoding,video)

skip_frame integer (decoding,video)

Make decoder discard processing depending on the frame type selected
by the option value.

Set to 1 to disable processing alpha (transparency). This works like the
‘gray’ flag in the flags option which skips chroma information
instead of alpha. Default is 0.

codec_whitelist list (input)

"," separated list of allowed decoders. By default all are allowed.

dump_separator string (input)

Separator used to separate the fields printed on the command line about the
Stream parameters.
For example to separate the fields with newlines and indention:

ffprobe -dump_separator "
" -i ~/videos/matrixbench_mpeg2.mpg

max_pixels integer (decoding/encoding,video)

Maximum number of pixels per image. This value can be used to avoid out of
memory failures due to large images.

apply_cropping bool (decoding,video)

Enable cropping if cropping parameters are multiples of the required
alignment for the left and top parameters. If the alignment is not met the
cropping will be partially applied to maintain alignment.
Default is 1 (enabled).
Note: The required alignment depends on if AV_CODEC_FLAG_UNALIGNED is set and the
CPU. AV_CODEC_FLAG_UNALIGNED cannot be changed from the command line. Also hardware
decoders will not apply left/top Cropping.

Decoders are configured elements in FFmpeg which allow the decoding of
multimedia streams.

When you configure your FFmpeg build, all the supported native decoders
are enabled by default. Decoders requiring an external library must be enabled
manually via the corresponding --enable-lib option. You can list all
available decoders using the configure option --list-decoders.

You can disable all the decoders with the configure option
--disable-decoders and selectively enable / disable single decoders
with the options --enable-decoder=DECODER /
--disable-decoder=DECODER.

The option -decoders of the ff* tools will display the list of
enabled decoders.

The lavc FLAC encoder used to produce buggy streams with high lpc values
(like the default value). This option makes it possible to decode such streams
correctly by using lavc’s old buggy lpc logic for decoding.

libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec.
Requires the presence of the libcelt headers and library during configuration.
You need to explicitly configure the build with --enable-libcelt.

libgsm allows libavcodec to decode the GSM full rate audio codec. Requires
the presence of the libgsm headers and library during configuration. You need
to explicitly configure the build with --enable-libgsm.

This decoder supports both the ordinary GSM and the Microsoft variant.

libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC)
audio codec. Requires the presence of the libilbc headers and library during
configuration. You need to explicitly configure the build with
--enable-libilbc.

libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate
Narrowband audio codec. Using it requires the presence of the
libopencore-amrnb headers and library during configuration. You need to
explicitly configure the build with --enable-libopencore-amrnb.

An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB
without this library.

libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate
Wideband audio codec. Using it requires the presence of the
libopencore-amrwb headers and library during configuration. You need to
explicitly configure the build with --enable-libopencore-amrwb.

An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB
without this library.

libopus allows libavcodec to decode the Opus Interactive Audio Codec.
Requires the presence of the libopus headers and library during
configuration. You need to explicitly configure the build with
--enable-libopus.

An FFmpeg native decoder for Opus exists, so users can decode Opus
without this library.

Specify the global palette used by the bitmaps. When stored in VobSub, the
palette is normally specified in the index file; in Matroska, the palette is
stored in the codec extra-data in the same format as in VobSub. In DVDs, the
palette is stored in the IFO file, and therefore not available when reading
from dumped VOB files.

Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext
subtitles. Requires the presence of the libzvbi headers and library during
configuration. You need to explicitly configure the build with
--enable-libzvbi.

List of teletext page numbers to decode. You may use the special * string to
match all pages. Pages that do not match the specified list are dropped.
Default value is *.

txt_chop_top

Discards the top teletext line. Default value is 1.

txt_format

Specifies the format of the decoded subtitles. The teletext decoder is capable
of decoding the teletext pages to bitmaps or to simple text, you should use
"bitmap" for teletext pages, because certain graphics and colors cannot be
expressed in simple text. You might use "text" for teletext based subtitles if
your application can handle simple text based subtitles. Default value is
bitmap.

txt_left

X offset of generated bitmaps, default is 0.

txt_top

Y offset of generated bitmaps, default is 0.

txt_chop_spaces

Chops leading and trailing spaces and removes empty lines from the generated
text. This option is useful for teletext based subtitles where empty spaces may
be present at the start or at the end of the lines or empty lines may be
present between the subtitle lines because of double-sized teletext characters.
Default value is 1.

txt_duration

Sets the display duration of the decoded teletext pages or subtitles in
milliseconds. Default value is 30000 which is 30 seconds.

Sets the opacity (0-255) of the teletext background. If
txt_transparent is not set, it only affects characters between a start
box and an end box, typically subtitles. Default value is 0 if
txt_transparent is set, 255 otherwise.

Encoders are configured elements in FFmpeg which allow the encoding of
multimedia streams.

When you configure your FFmpeg build, all the supported native encoders
are enabled by default. Encoders requiring an external library must be enabled
manually via the corresponding --enable-lib option. You can list all
available encoders using the configure option --list-encoders.

You can disable all the encoders with the configure option
--disable-encoders and selectively enable / disable single encoders
with the options --enable-encoder=ENCODER /
--disable-encoder=ENCODER.

The option -encoders of the ff* tools will display the list of
enabled encoders.

This encoder is the default AAC encoder, natively implemented into FFmpeg. Its
quality is on par or better than libfdk_aac at the default bitrate of 128kbps.
This encoder also implements more options, profiles and samplerates than
other encoders (with only the AAC-HE profile pending to be implemented) so this
encoder has become the default and is the recommended choice.

Set bit rate in bits/s. Setting this automatically activates constant bit rate
(CBR) mode. If this option is unspecified it is set to 128kbps.

q

Set quality for variable bit rate (VBR) mode. This option is valid only using
the ffmpeg command-line tool. For library interface users, use
global_quality.

cutoff

Set cutoff frequency. If unspecified will allow the encoder to dynamically
adjust the cutoff to improve clarity on low bitrates.

aac_coder

Set AAC encoder coding method. Possible values:

‘twoloop’

Two loop searching (TLS) method.

This method first sets quantizers depending on band thresholds and then tries
to find an optimal combination by adding or subtracting a specific value from
all quantizers and adjusting some individual quantizer a little. Will tune
itself based on whether aac_is, aac_ms and aac_pns
are enabled.
This is the default choice for a coder.

‘anmr’

Average noise to mask ratio (ANMR) trellis-based solution.

This is an experimental coder which currently produces a lower quality, is more
unstable and is slower than the default twoloop coder but has potential.
Currently has no support for the aac_is or aac_pns options.
Not currently recommended.

‘fast’

Constant quantizer method.

This method sets a constant quantizer for all bands. This is the fastest of all
the methods and has no rate control or support for aac_is or
aac_pns.
Not recommended.

aac_ms

Sets mid/side coding mode. The default value of "auto" will automatically use
M/S with bands which will benefit from such coding. Can be forced for all bands
using the value "enable", which is mainly useful for debugging or disabled using
"disable".

aac_is

Sets intensity stereo coding tool usage. By default, it’s enabled and will
automatically toggle IS for similar pairs of stereo bands if it’s beneficial.
Can be disabled for debugging by setting the value to "disable".

aac_pns

Uses perceptual noise substitution to replace low entropy high frequency bands
with imperceptible white noise during the decoding process. By default, it’s
enabled, but can be disabled for debugging purposes by using "disable".

aac_tns

Enables the use of a multitap FIR filter which spans through the high frequency
bands to hide quantization noise during the encoding process and is reverted
by the decoder. As well as decreasing unpleasant artifacts in the high range
this also reduces the entropy in the high bands and allows for more bits to
be used by the mid-low bands. By default it’s enabled but can be disabled for
debugging by setting the option to "disable".

aac_ltp

Enables the use of the long term prediction extension which increases coding
efficiency in very low bandwidth situations such as encoding of voice or
solo piano music by extending constant harmonic peaks in bands throughout
frames. This option is implied by profile:a aac_low and is incompatible with
aac_pred. Use in conjunction with -ar to decrease the samplerate.

aac_pred

Enables the use of a more traditional style of prediction where the spectral
coefficients transmitted are replaced by the difference of the current
coefficients minus the previous "predicted" coefficients. In theory and sometimes
in practice this can improve quality for low to mid bitrate audio.
This option implies the aac_main profile and is incompatible with aac_ltp.

profile

Sets the encoding profile, possible values:

‘aac_low’

The default, AAC "Low-complexity" profile. Is the most compatible and produces
decent quality.

‘mpeg2_aac_low’

Equivalent to -profile:a aac_low -aac_pns 0. PNS was introduced with the
MPEG4 specifications.

‘aac_ltp’

Long term prediction profile, is enabled by and will enable the aac_ltp
option. Introduced in MPEG4.

‘aac_main’

Main-type prediction profile, is enabled by and will enable the aac_pred
option. Introduced in MPEG2.

These encoders implement part of ATSC A/52:2010 and ETSI TS 102 366, as well as
the undocumented RealAudio 3 (a.k.a. dnet).

The ac3 encoder uses floating-point math, while the ac3_fixed
encoder only uses fixed-point integer math. This does not mean that one is
always faster, just that one or the other may be better suited to a
particular system. The floating-point encoder will generally produce better
quality audio for a given bitrate. The ac3_fixed encoder is not the
default codec for any of the output formats, so it must be specified explicitly
using the option -acodec ac3_fixed in order to use it.

The AC-3 metadata options are used to set parameters that describe the audio,
but in most cases do not affect the audio encoding itself. Some of the options
do directly affect or influence the decoding and playback of the resulting
bitstream, while others are just for informational purposes. A few of the
options will add bits to the output stream that could otherwise be used for
audio data, and will thus affect the quality of the output. Those will be
indicated accordingly with a note in the option list below.

These parameters are described in detail in several publicly-available
documents.

Center Mix Level. The amount of gain the decoder should apply to the center
channel when downmixing to stereo. This field will only be written to the
bitstream if a center channel is present. The value is specified as a scale
factor. There are 3 valid values:

0.707

Apply -3dB gain

0.595

Apply -4.5dB gain (default)

0.500

Apply -6dB gain

-surround_mixlev level

Surround Mix Level. The amount of gain the decoder should apply to the surround
channel(s) when downmixing to stereo. This field will only be written to the
bitstream if one or more surround channels are present. The value is specified
as a scale factor. There are 3 valid values:

Audio Production Information is optional information describing the mixing
environment. Either none or both of the fields are written to the bitstream.

-mixing_level number

Mixing Level. Specifies peak sound pressure level (SPL) in the production
environment when the mix was mastered. Valid values are 80 to 111, or -1 for
unknown or not indicated. The default value is -1, but that value cannot be
used if the Audio Production Information is written to the bitstream. Therefore,
if the room_type option is not the default value, the mixing_level
option must not be -1.

-room_type type

Room Type. Describes the equalization used during the final mixing session at
the studio or on the dubbing stage. A large room is a dubbing stage with the
industry standard X-curve equalization; a small room has flat equalization.
This field will not be written to the bitstream if both the mixing_level
option and the room_type option have the default values.

Copyright Indicator. Specifies whether a copyright exists for this audio.

0

off

No Copyright Exists (default)

1

on

Copyright Exists

-dialnorm value

Dialogue Normalization. Indicates how far the average dialogue level of the
program is below digital 100% full scale (0 dBFS). This parameter determines a
level shift during audio reproduction that sets the average volume of the
dialogue to a preset level. The goal is to match volume level between program
sources. A value of -31dB will result in no volume level change, relative to
the source volume, during audio reproduction. Valid values are whole numbers in
the range -31 to -1, with -31 being the default.

-dsur_mode mode

Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround
(Pro Logic). This field will only be written to the bitstream if the audio
stream is stereo. Using this option does NOT mean the encoder will actually
apply Dolby Surround processing.

0

notindicated

Not Indicated (default)

1

off

Not Dolby Surround Encoded

2

on

Dolby Surround Encoded

-original boolean

Original Bit Stream Indicator. Specifies whether this audio is from the
original source and not a copy.

The extended bitstream options are part of the Alternate Bit Stream Syntax as
specified in Annex D of the A/52:2010 standard. It is grouped into 2 parts.
If any one parameter in a group is specified, all values in that group will be
written to the bitstream. Default values are used for those that are written
but have not been specified. If the mixing levels are written, the decoder
will use these values instead of the ones specified in the center_mixlev
and surround_mixlev options if it supports the Alternate Bit Stream
Syntax.

Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone
encoding (multi-channel matrixed to 2.0 for use with headphones). Using this
option does NOT mean the encoder will actually apply Dolby Headphone
processing.

Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This
is an optional AC-3 feature that increases quality by selectively encoding
the left/right channels as mid/side. This option is enabled by default, and it
is highly recommended that it be left as enabled except for testing purposes.

cutoff frequency

Set lowpass cutoff frequency. If unspecified, the encoder selects a default
determined by various other encoding parameters.

These options are only valid for the floating-point encoder and do not exist
for the fixed-point encoder due to the corresponding features not being
implemented in fixed-point.

-channel_coupling boolean

Enables/Disables use of channel coupling, which is an optional AC-3 feature
that increases quality by combining high frequency information from multiple
channels into a single channel. The per-channel high frequency information is
sent with less accuracy in both the frequency and time domains. This allows
more bits to be used for lower frequencies while preserving enough information
to reconstruct the high frequencies. This option is enabled by default for the
floating-point encoder and should generally be left as enabled except for
testing purposes or to increase encoding speed.

-1

auto

Selected by Encoder (default)

0

off

Disable Channel Coupling

1

on

Enable Channel Coupling

-cpl_start_band number

Coupling Start Band. Sets the channel coupling start band, from 1 to 15. If a
value higher than the bandwidth is used, it will be reduced to 1 less than the
coupling end band. If auto is used, the start band will be determined by
the encoder based on the bit rate, sample rate, and channel layout. This option
has no effect if channel coupling is disabled.

This is a native FFmpeg encoder for the Opus format. Currently its in development and
only implements the CELT part of the codec. Its quality is usually worse and at best
is equal to the libopus encoder.

The libfdk-aac library is based on the Fraunhofer FDK AAC code from
the Android project.

Requires the presence of the libfdk-aac headers and library during
configuration. You need to explicitly configure the build with
--enable-libfdk-aac. The library is also incompatible with GPL,
so if you allow the use of GPL, you should configure with
--enable-gpl --enable-nonfree --enable-libfdk-aac.

This encoder is considered to produce output on par or worse at 128kbps to the
the native FFmpeg AAC encoder but can often produce better
sounding audio at identical or lower bitrates and has support for the
AAC-HE profiles.

VBR encoding, enabled through the vbr or flags
+qscale options, is experimental and only works with some
combinations of parameters.

Support for encoding 7.1 audio is only available with libfdk-aac 0.1.3 or
higher.

Most libopus options are modelled after the opusenc utility from
opus-tools. The following is an option mapping chart describing options
supported by the libopus wrapper, and their opusenc-equivalent
in parentheses.

b (bitrate)

Set the bit rate in bits/s. FFmpeg’s b option is
expressed in bits/s, while opusenc’s bitrate in
kilobits/s.

vbr (vbr, hard-cbr, and cvbr)

Set VBR mode. The FFmpeg vbr option has the following
valid arguments, with the opusenc equivalent options
in parentheses:

‘off (hard-cbr)’

Use constant bit rate encoding.

‘on (vbr)’

Use variable bit rate encoding (the default).

‘constrained (cvbr)’

Use constrained variable bit rate encoding.

compression_level (comp)

Set encoding algorithm complexity. Valid options are integers in
the 0-10 range. 0 gives the fastest encodes but lower quality, while 10
gives the highest quality but slowest encoding. The default is 10.

frame_duration (framesize)

Set maximum frame size, or duration of a frame in milliseconds. The
argument must be exactly the following: 2.5, 5, 10, 20, 40, 60. Smaller
frame sizes achieve lower latency but less quality at a given bitrate.
Sizes greater than 20ms are only interesting at fairly low bitrates.
The default is 20ms.

packet_loss (expect-loss)

Set expected packet loss percentage. The default is 0.

application (N.A.)

Set intended application type. Valid options are listed below:

‘voip’

Favor improved speech intelligibility.

‘audio’

Favor faithfulness to the input (the default).

‘lowdelay’

Restrict to only the lowest delay modes.

cutoff (N.A.)

Set cutoff bandwidth in Hz. The argument must be exactly one of the
following: 4000, 6000, 8000, 12000, or 20000, corresponding to
narrowband, mediumband, wideband, super wideband, and fullband
respectively. The default is 0 (cutoff disabled).

mapping_family (mapping_family)

Set channel mapping family to be used by the encoder. The default value of -1
uses mapping family 0 for mono and stereo inputs, and mapping family 1
otherwise. The default also disables the surround masking and LFE bandwidth
optimzations in libopus, and requires that the input contains 8 channels or
fewer.

Other values include 0 for mono and stereo, 1 for surround sound with masking
and LFE bandwidth optimizations, and 255 for independent streams with an
unspecified channel layout.

Shine is a fixed-point MP3 encoder. It has a far better performance on
platforms without an FPU, e.g. armel CPUs, and some phones and tablets.
However, as it is more targeted on performance than quality, it is not on par
with LAME and other production-grade encoders quality-wise. Also, according to
the project’s homepage, this encoder may not be free of bugs as the code was
written a long time ago and the project was dead for at least 5 years.

This encoder only supports stereo and mono input. This is also CBR-only.

The following options are supported by the libtwolame wrapper. The
twolame-equivalent options follow the FFmpeg ones and are in
parentheses.

b (-b)

Set bitrate expressed in bits/s for CBR. twolameb
option is expressed in kilobits/s. Default value is 128k.

q (-V)

Set quality for experimental VBR support. Maximum value range is
from -50 to 50, useful range is from -10 to 10. The higher the
value, the better the quality. This option is valid only using the
ffmpeg command-line tool. For library interface users,
use global_quality.

mode (--mode)

Set the mode of the resulting audio. Possible values:

‘auto’

Choose mode automatically based on the input. This is the default.

‘stereo’

Stereo

‘joint_stereo’

Joint stereo

‘dual_channel’

Dual channel

‘mono’

Mono

psymodel (--psyc-mode)

Set psychoacoustic model to use in encoding. The argument must be
an integer between -1 and 4, inclusive. The higher the value, the
better the quality. The default value is 3.

energy_levels (--energy)

Enable energy levels extensions when set to 1. The default value is
0 (disabled).

error_protection (--protect)

Enable CRC error protection when set to 1. The default value is 0
(disabled).

copyright (--copyright)

Set MPEG audio copyright flag when set to 1. The default value is 0
(disabled).

original (--original)

Set MPEG audio original flag when set to 1. The default value is 0
(disabled).

Set bitrate expressed in bits/s for ABR. oggenc-b is
expressed in kilobits/s.

q (-q)

Set constant quality setting for VBR. The value should be a float
number in the range of -1.0 to 10.0. The higher the value, the better
the quality. The default value is ‘3.0’.

This option is valid only using the ffmpeg command-line tool.
For library interface users, use global_quality.

cutoff (--advanced-encode-option lowpass_frequency=N)

Set cutoff bandwidth in Hz, a value of 0 disables cutoff. oggenc’s
related option is expressed in kHz. The default value is ‘0’ (cutoff
disabled).

minrate (-m)

Set minimum bitrate expressed in bits/s. oggenc-m is
expressed in kilobits/s.

maxrate (-M)

Set maximum bitrate expressed in bits/s. oggenc-M is
expressed in kilobits/s. This only has effect on ABR mode.

iblock (--advanced-encode-option impulse_noisetune=N)

Set noise floor bias for impulse blocks. The value is a float number from
-15.0 to 0.0. A negative bias instructs the encoder to pay special attention
to the crispness of transients in the encoded audio. The tradeoff for better
transient response is a higher bitrate.

The following shared options are effective for this encoder. Only special notes
about this particular encoder will be documented here. For the general meaning
of the options, see the Codec Options chapter.

frame_size (--blocksize)

For this encoder, the range for this option is between 128 and 131072. Default
is automatically decided based on sample rate and number of channel.

For the complete formula of calculating default, see
libavcodec/wavpackenc.c.

Specifies the number of chunks to split frames into, between 1 and 64. This
permits multithreaded decoding of large frames, potentially at the cost of
data-rate. The encoder may modify this value to divide frames evenly.

Default value is 1.

compressor integer

Specifies the second-stage compressor to use. If set to none,
chunks will be limited to 1, as chunked uncompressed frames offer no
benefit.

This encoder requires the presence of the libopenh264 headers and
library during configuration. You need to explicitly configure the
build with --enable-libopenh264. The library is detected using
pkg-config.

The following global options are mapped to internal libtheora options
which affect the quality and the bitrate of the encoded stream.

b

Set the video bitrate in bit/s for CBR (Constant Bit Rate) mode. In
case VBR (Variable Bit Rate) mode is enabled this option is ignored.

flags

Used to enable constant quality mode (VBR) encoding through the
qscale flag, and to enable the pass1 and pass2
modes.

g

Set the GOP size.

global_quality

Set the global quality as an integer in lambda units.

Only relevant when VBR mode is enabled with flags +qscale. The
value is converted to QP units by dividing it by FF_QP2LAMBDA,
clipped in the [0 - 10] range, and then multiplied by 6.3 to get a
value in the native libtheora range [0-63]. A higher value corresponds
to a higher quality.

q

Enable VBR mode when set to a non-negative value, and set constant
quality value as a double floating point value in QP units.

The value is clipped in the [0-10] range, and then multiplied by 6.3
to get a value in the native libtheora range [0-63].

This option is valid only using the ffmpeg command-line
tool. For library interface users, use global_quality.

The following options are supported by the libvpx wrapper. The
vpxenc-equivalent options or values are listed in parentheses
for easy migration.

To reduce the duplication of documentation, only the private options
and some others requiring special attention are documented here. For
the documentation of the undocumented generic options, see
the Codec Options chapter.

To get more documentation of the libvpx options, invoke the command
ffmpeg -h encoder=libvpx, ffmpeg -h encoder=libvpx-vp9 or
vpxenc --help. Further information is available in the libvpx API
documentation.

b (target-bitrate)

Set bitrate in bits/s. Note that FFmpeg’s b option is
expressed in bits/s, while vpxenc’s target-bitrate is in
kilobits/s.

Set number of bits which should be loaded into the rc buffer before decoding
starts. Note vpxenc’s option is specified in milliseconds, the libvpx
wrapper converts this value as follows:
rc_init_occupancy * 1000 / bitrate.

undershoot-pct

Set datarate undershoot (min) percentage of the target bitrate.

overshoot-pct

Set datarate overshoot (max) percentage of the target bitrate.

skip_threshold (drop-frame)

qcomp (bias-pct)

maxrate (maxsection-pct)

Set GOP max bitrate in bits/s. Note vpxenc’s option is specified as a
percentage of the target bitrate, the libvpx wrapper converts this value as
follows: (maxrate * 100 / bitrate).

minrate (minsection-pct)

Set GOP min bitrate in bits/s. Note vpxenc’s option is specified as a
percentage of the target bitrate, the libvpx wrapper converts this value as
follows: (minrate * 100 / bitrate).

minrate, maxrate, b end-usage=cbr

(minrate == maxrate == bitrate).

crf (end-usage=cq, cq-level)

tune (tune)

‘psnr (psnr)’

‘ssim (ssim)’

quality, deadline (deadline)

‘best’

Use best quality deadline. Poorly named and quite slow, this option should be
avoided as it may give worse quality output than good.

‘good’

Use good quality deadline. This is a good trade-off between speed and quality
when used with the cpu-used option.

‘realtime’

Use realtime quality deadline.

speed, cpu-used (cpu-used)

Set quality/speed ratio modifier. Higher values speed up the encode at the cost
of quality.

nr (noise-sensitivity)

static-thresh

Set a change threshold on blocks below which they will be skipped by the
encoder.

slices (token-parts)

Note that FFmpeg’s slices option gives the total number of partitions,
while vpxenc’s token-parts is given as
log2(partitions).

max-intra-rate

Set maximum I-frame bitrate as a percentage of the target bitrate. A value of 0
means unlimited.

force_key_frames

VPX_EFLAG_FORCE_KF

Alternate reference frame related

auto-alt-ref

Enable use of alternate reference frames (2-pass only).

arnr-max-frames

Set altref noise reduction max frame count.

arnr-type

Set altref noise reduction filter type: backward, forward, centered.

arnr-strength

Set altref noise reduction filter strength.

rc-lookahead, lag-in-frames (lag-in-frames)

Set number of frames to look ahead for frametype and ratecontrol.

error-resilient

Enable error resiliency features.

VP9-specific options

lossless

Enable lossless mode.

tile-columns

Set number of tile columns to use. Note this is given as
log2(tile_columns). For example, 8 tile columns would be requested by
setting the tile-columns option to 3.

tile-rows

Set number of tile rows to use. Note this is given as log2(tile_rows).
For example, 4 tile rows would be requested by setting the tile-rows
option to 2.

libwebp is Google’s official encoder for WebP images. It can encode in either
lossy or lossless mode. Lossy images are essentially a wrapper around a VP8
frame. Lossless images are a separate codec developed by Google.

Currently, libwebp only supports YUV420 for lossy and RGB for lossless due
to limitations of the format and libwebp. Alpha is supported for either mode.
Because of API limitations, if RGB is passed in when encoding lossy or YUV is
passed in for encoding lossless, the pixel format will automatically be
converted using functions from libwebp. This is not ideal and is done only for
convenience.

For lossy, this is a quality/speed tradeoff. Higher values give better quality
for a given size at the cost of increased encoding time. For lossless, this is
a size/speed tradeoff. Higher values give smaller size at the cost of increased
encoding time. More specifically, it controls the number of extra algorithms
and compression tools used, and varies the combination of these tools. This
maps to the method option in libwebp. The valid range is 0 to 6.
Default is 4.

-qscale float

For lossy encoding, this controls image quality, 0 to 100. For lossless
encoding, this controls the effort and time spent at compressing more. The
default value is 75. Note that for usage via libavcodec, this option is called
global_quality and must be multiplied by FF_QP2LAMBDA.

-preset type

Configuration preset. This does some automatic settings based on the general
type of the image.

Many libx264 encoder options are mapped to FFmpeg global codec
options, while unique encoder options are provided through private
options. Additionally the x264opts and x264-params
private options allows one to pass a list of key=value tuples as accepted
by the libx264 x264_param_parse function.

x264 supports 8- to 10-bit color spaces. The exact bit depth is controlled at
x264’s configure time. FFmpeg only supports one bit depth in one particular
build. In other words, it is not possible to build one FFmpeg with multiple
versions of x264 with different bit depths.

The following options are supported by the libx264 wrapper. The
x264-equivalent options or values are listed in parentheses
for easy migration.

To reduce the duplication of documentation, only the private options
and some others requiring special attention are documented here. For
the documentation of the undocumented generic options, see
the Codec Options chapter.

To get a more accurate and extensive documentation of the libx264
options, invoke the command x264 --fullhelp or consult
the libx264 documentation.

b (bitrate)

Set bitrate in bits/s. Note that FFmpeg’s b option is
expressed in bits/s, while x264’s bitrate is in
kilobits/s.

bf (bframes)

g (keyint)

qmin (qpmin)

Minimum quantizer scale.

qmax (qpmax)

Maximum quantizer scale.

qdiff (qpstep)

Maximum difference between quantizer scales.

qblur (qblur)

Quantizer curve blur

qcomp (qcomp)

Quantizer curve compression factor

refs (ref)

Number of reference frames each P-frame can use. The range is from 0-16.

Argument is a list of key=value couples separated by
":". In filter and psy-rd options that use ":" as a separator
themselves, use "," instead. They accept it as well since long ago but this
is kept undocumented for some reason.

The following options are supported by the libxvid wrapper. Some of
the following options are listed but are not documented, and
correspond to shared codec options. See the Codec
Options chapter for their documentation. The other shared options
which are not listed have no effect for the libxvid encoder.

b

g

qmin

qmax

mpeg_quant

threads

bf

b_qfactor

b_qoffset

flags

Set specific encoding flags. Possible values:

‘mv4’

Use four motion vector by macroblock.

‘aic’

Enable high quality AC prediction.

‘gray’

Only encode grayscale.

‘gmc’

Enable the use of global motion compensation (GMC).

‘qpel’

Enable quarter-pixel motion compensation.

‘cgop’

Enable closed GOP.

‘global_header’

Place global headers in extradata instead of every keyframe.

trellis

me_method

Set motion estimation method. Possible values in decreasing order of
speed and increasing order of quality:

In the default mode of operation the encoder has to honor frame constraints
(i.e. not produce frames with size bigger than requested) while still making
output picture as good as possible.
A frame containing a lot of small details is harder to compress and the encoder
would spend more time searching for appropriate quantizers for each slice.

Setting a higher bits_per_mb limit will improve the speed.

For the fastest encoding speed set the qscale parameter (4 is the
recommended value) and do not set a size constraint.

When global_quality is specified, a quality-based mode is used.
Specifically this means either

- CQP - constant quantizer scale, when the qscale codec flag is
also set (the -qscale ffmpeg option).

- LA_ICQ - intelligent constant quality with lookahead, when the
look_ahead option is also set.

- ICQ – intelligent constant quality otherwise.

Otherwise, a bitrate-based mode is used. For all of those, you should specify at
least the desired average bitrate with the b option.

- LA - VBR with lookahead, when the look_ahead option is specified.

- VCM - video conferencing mode, when the vcm option is set.

- CBR - constant bitrate, when maxrate is specified and equal to
the average bitrate.

- VBR - variable bitrate, when maxrate is specified, but is higher
than the average bitrate.

- AVBR - average VBR mode, when maxrate is not specified. This mode
is further configured by the avbr_accuracy and
avbr_convergence options.

Note that depending on your system, a different mode than the one you specified
may be selected by the encoder. Set the verbosity level to verbose or
higher to see the actual settings used by the QSV runtime.

B-frames are supported, but the output stream is always in encode order rather than display
order. If B-frames are enabled, it may be necessary to use the vp9_raw_reorder
bitstream filter to modify the output stream to display frames in the correct order.

Only normal frames are produced - the vp9_superframe bitstream filter may be
required to produce a stream usable with all decoders.

SMPTE VC-2 (previously BBC Dirac Pro). This codec was primarily aimed at
professional broadcasting but since it supports yuv420, yuv422 and yuv444 at
8 (limited range or full range), 10 or 12 bits, this makes it suitable for
other tasks which require low overhead and low compression (like screen
recording).

Enables field coding when set (e.g. to tt - top field first) for interlaced
inputs. Should increase compression with interlaced content as it splits the
fields and encodes each separately.

wavelet_depth

Sets the total amount of wavelet transforms to apply, between 1 and 5 (default).
Lower values reduce compression and quality. Less capable decoders may not be
able to handle values of wavelet_depth over 3.

wavelet_type

Sets the transform type. Currently only 5_3 (LeGall) and 9_7
(Deslauriers-Dubuc)
are implemented, with 9_7 being the one with better compression and thus
is the default.

slice_width

slice_height

Sets the slice size for each slice. Larger values result in better compression.
For compatibility with other more limited decoders use slice_width of
32 and slice_height of 8.

tolerance

Sets the undershoot tolerance of the rate control system in percent. This is
to prevent an expensive search from being run.

qm

Sets the quantization matrix preset to use by default or when wavelet_depth
is set to 5

- default
Uses the default quantization matrix from the specifications, extended with
values for the fifth level. This provides a good balance between keeping detail
and omitting artifacts.

- flat
Use a completely zeroed out quantization matrix. This increases PSNR but might
reduce perception. Use in bogus benchmarks.

When set to 1, enable a work-around that makes the number of pixel rows
even in all subtitles. This fixes a problem with some players that
cut off the bottom row if the number is odd. The work-around just adds
a fully transparent row if needed. The overhead is low, typically
one byte per subtitle on average.

For details about the authorship, see the Git history of the project
(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
git log in the FFmpeg source directory, or browsing the
online repository at http://source.ffmpeg.org.

Maintainers for the specific components are listed in the file
MAINTAINERS in the source code tree.